package com.gf.common.util;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.context.support.ClassPathXmlApplicationContext;

/**
 * 
 * 通过该类，任何其他类中可以静态获取Spring中的配置信息
 * @author zhuguifeng
 */
public class SpringUtils implements ApplicationContextAware, DisposableBean {
	private static ApplicationContext applicationContext = null;
	private static final Log LOGGER = LogFactory.getLog(SpringUtils.class);

    /**
     * 取得存储在静态变量中的ApplicationContext.
     */
    public static ApplicationContext getApplicationContext() {
            assertContextInjected();
            return applicationContext;
    }

    /**
     * 从静态变量applicationContext中取得Bean, 自动转型为所赋值对象的类型.
     */
    @SuppressWarnings("unchecked")
	public static <T> T getBean(String name) {
            assertContextInjected();
            return (T) applicationContext.getBean(name);
    }

    /**
     * 从静态变量applicationContext中取得Bean, 自动转型为所赋值对象的类型.
     */
    public static <T> T getBean(Class<T> requiredType) {
            assertContextInjected();
            return applicationContext.getBean(requiredType);
    }

    /**
     * 清除SpringContextHolder中的ApplicationContext为Null.
     */
    public static void clearHolder() {
            LOGGER.debug("清除SpringUtils中的ApplicationContext:" + applicationContext);
            applicationContext = null;
    }

    /**
     * 实现ApplicationContextAware接口, 注入Context到静态变量中.
     */
    @Override
    public void setApplicationContext(ApplicationContext applicationContext) {
            LOGGER.debug("注入ApplicationContext到SpringContextHolder:" + applicationContext);

            if (SpringUtils.applicationContext != null) {
                    LOGGER.warn("SpringUtils中的ApplicationContext被覆盖, 原有ApplicationContext为:"
                                    + SpringUtils.applicationContext);
            }

            SpringUtils.applicationContext = applicationContext; //NOSONAR
    }

    /**
     * 实现DisposableBean接口, 在Context关闭时清理静态变量.
     */
    @Override
    public void destroy() throws Exception {
            SpringUtils.clearHolder();
    }

    /**
     * 检查ApplicationContext不为空，如果为空采用本地方式加载.
     */
    private static void assertContextInjected() {
    	if(applicationContext == null) {
    		LOGGER.warn("applicaitonContext属性未注入, 请在applicationContext.xml中定义SpringUtils.");
    		applicationContext = new ClassPathXmlApplicationContext("config/context/applicationContext.xml");
    	}
    }
	
}
